Posting a readonly field

Question

Hello,
I generated a create uix file based on a bc4j view object. Then I databinded a value to the field GeaendertVon.
This value must not be changed by the user, but setting it to readonly="true" or rendered="false" (the preferred solution) gives the following error if I press create:
JBO-26041: Failed to post data to database during "Insert": SQL Statement "BEGIN INSERT INTO MASKEN(,STUFE,GEAENDERT_VON,GEAENDERT_AM) VALUES (:1,:2,:3,:4) RETURNING ID INTO :5; END;".
NAME
this the uix fragment:
<contents>
<bc4j:viewObjectScope name="MaskenVOInst">
<contents>
<bc4j:rowScope name="CreateMaskenVOInst">
<contents>
<bc4j:messageInput attrName="Id"/>
<bc4j:messageInput attrName="Name"/>
<bc4j:messageInput attrName="Stufe"/>
<bc4j:messageInput attrName="GeaendertVon" data:text="username@loginData" readOnly="true"/>
<bc4j:messageInput attrName="GeaendertAm" />
</contents>
</bc4j:rowScope>
</contents>
</bc4j:viewObjectScope>
</contents>

Answer 1

hello, this is my create handler (as been generated by JDeveloper):
<event name="apply">
<bc4j:findRootAppModule name="MaskenVOInstAppModule">
<bc4j:findViewObject name="MaskenVOInst">
<bc4j:findRow name="CreateMaskenVOInst">
<bc4j:setPageProperty name="key">
<bc4j:stringKey/>
</bc4j:setPageProperty>
<!-- set each attribute explicitly -->
<bc4j:setAttribute name="Id"/>
<bc4j:setAttribute name="Name"/>
<bc4j:setAttribute name="Stufe"/>
<bc4j:setAttribute name="GeaendertVon"/>
<bc4j:setAttribute name="GeaendertAm"/>
<bc4j:insertRow/>
<bc4j:commit/>
<bc4j:executeQuery/>
<ctrl:go name="masken_v" redirect="true"/>
</bc4j:findRow>
</bc4j:findViewObject>
</bc4j:findRootAppModule>
</event>